Cofactor disorders of mitochondrial energy metabolism are a heterogeneous group of diseases with a wide variety of clinical symptoms, particular metabolic profiles and variable enzymatic defects. Mutations in NFU1, BOLA3, LIAS and IBA57 have been identified in patients with deficient lipoic acid-dependent enzymatic activities and defects in the assembly and activity of the mitochondrial respiratory chain complexes. Here, we report a patient with an early onset fatal lactic acidosis presenting a biochemical phenotype compatible with a combined defect of pyruvate dehydrogenase (PDHC) and 2-ketoglutarate dehydrogenase (2-KGDH) activities, which suggested a deficiency in lipoic acid metabolism. Immunostaining analysis showed that lipoylated E2-PDH and E2-KGDH were extremely reduced in this patient. However, the absence of glycine elevation, the normal activity of the glycine cleavage system and the normal lipoylation of the H protein suggested a defect of lipoic acid transfer to particular proteins rather than a general impairment of lipoic acid biosynthesis as the potential cause of the disease. By analogy with yeast metabolism, we postulated LIPT1 as the altered candidate gene causing the disease. Sequence analysis of the human LIPT1 identified two heterozygous missense mutations (c.212C>T and c.292C>G), segregating in different alleles. Functional complementation experiments in patient's fibroblasts demonstrated that these mutations are disease-causing and that LIPT1 protein is required for lipoylation and activation of 2-ketoacid dehydrogenases in humans. These findings expand the spectrum of genetic defects associated with lipoic acid metabolism and provide the first evidence of a lipoic acid transfer defect in humans.

Background: MicroRNAs (miRNAs) have been reported as deregulated in active brain lesions derived from patients with multiple sclerosis (MS). In there, these post-transcriptional regulators may elicit very important effects but proper identification of miRNA candidates as potential biomarkers and/or therapeutic targets is scarcely available. Objective: The aim of the study was to detect the presence of a set of candidate miRNAs in cell-free cerebrospinal fluid (CSF) and to determine their association with gadolinium-enhancing (Gd+) lesions in order to assess their value as biomarkers of MS activity. Methods: Assessment of 28 miRNA candidates in cell-free CSF collected from 46 patients with MS (26 Gd+ and 20 Gd− patients) was performed by TaqMan assays and qPCR. Variations in their relative abundance were analyzed by the Mann-Whitney U test and further evaluated by receiver operating characteristic (ROC) analysis. Signaling pathways and biological functions of miRNAs were analyzed using bioinformatic tools (miRTarBase, Enrichr, REVIGO, and Cytoscape softwares). Results: Seven out of 28 miRNA candidates were detected in at least 75% of CSF samples. Consistent increase of miR-21 and miR-146a/b was found in Gd+ MS patients. This increase was in parallel to the number of Gd+ lesions and neurofilament light chain (NF-L) levels. Gene Ontology enrichment analysis revealed that the target genes of these miRNAs are involved in biological processes of key relevance such as apoptosis, cell migration and proliferation, and in cytokine-mediated signaling pathways. Conclusion: Levels of miR-21 and miR-146a/b in cell-free CSF may represent valuable biomarkers to identify patients with active MS lesions.

Background: MicroRNAs (miRNAs) are non-coding RNAs that regulate cellular processes by controlling protein translation and mRNA degradation. Objective: We aimed to explore the miRNA signature of multiple sclerosis (MS) patients versus controls and the possibility that patients with lipid-specific oligolconal IgM bands (LS_OCMB), a predictor of a more severe disease course, may have a distinct profile. Methods: An extensive profile of 754 miRNAs was evaluated in the cerebrospinal fluid (CSF) of 14 women using TaqMan low-density arrays. Differentially expressed miRNAs together with others previously identified in the literature were validated in an extended sample of 86 MS patients (39 LS_OCMB+) and 55 controls. Results: We detected higher levels of miR-150 in MS patients and especially in those with LS_OCMB+. Other miRNAs (miR-328, miR-30a-5p and miR-645) were up-regulated in MS patients compared to controls while miR-21, miR-199a-3p, miR-191, miR-365, miR-106a and miR-146a showed down-regulated expression. Considering only patients with LS_OCMB+, we also detected up-regulation of miR-30a-5p, miR-150 and miR-645 and down-regulation of miR-191 compared to controls. Conclusion: Our study confirms the recent findings regarding the deregulated expression of miR-150 not only with MS but also with the presence of LS_OCMB. This study highlights the potential utility of miRNAs in CSF as biomarkers for MS.